1. Field of the Invention
This relates generally to fluid pumps and more particularly to an improved rotary pump or compressor, adapted to be more efficient in operation, have reduced wear and to be more economical to operate. The compressor of the invention utilizes gear rotors having hollow interiors from which the fluid to be compressed is introduced.
2. Prior Art
Rotary mechanisms that use gear like rotors having hollow centers have been known and used in the past. One such apparatus is shown in U.S. Pat. No. 1,076,299. This patent teaches a steam motor having two gear rotors in which each rotor, which has a plurality of slots therein, rotates around an internal sleeve having but a single slot therein such that steam can pass from the center of the rotor only when a slot in the rotor is aligned with the single slot in the internal sleeve. Thus steam can pass out of the center of the rotor only when the rotor is in a predetermined position. The expanding steam, exiting out of the center of each rotor, when the rotors are in the proper position, tries to drive the two rotors in oppoiste directions so as to cause the device to be a motor.
The apparatus described in this patent is not suitable for use as a compressor and is very inefficient as a motor because the steam, after it passes through the slots into the region between the intermeshing teeth of the rotors, expands and applies an equal force in all directions. Thus, it, the expanding steam, also applies a force opposite to the direction the impellers are desired to turn, and this severely reduces the efficiency of the apparatus.
U.S. Pat. No. 1,418,741 also teaches a rotary mechanism having hollow, multiple slotted, rotors mounted on spindles having but a single slot therein. This pump also tends to be inefficient. The pressurizing action occurs only when two teeth of the rotor engage. Thus as the teeth engage the pressure begins to increase and continues to increase until it is suddenly relieved when the slot in the rotor comes into alignment with the slot in the sleeve. This sudden relieving of the pressure causes irregular motions in the apparatus and a severe reduction in efficiency.
U.S. Pat. No. 3,259,073 describes a pump having a sun gear with a hollow internal chamber connected to an axially disposed outlet and surrounded with a plurality of planetary gears. The sun gear is provided with a plurality of openings communicating with its internal chamber and each opening is further provided with a check valve. These check valves are provided in order to prevent the compressed fluid, being pumped into the central chamber of the sun gear by the planetary gears, from flowing back out of the internal chamber.
None of these references teach the concept of drawing the fluid, being pumped, out of the center of the impellers by supplying each of the impellers with a plurality of slots, substantially all of which are open at all times. The fluid so drawn out of the center of the impellers is compressed by the rotary action of the impellers and the efficiency of the pump is significantly increased.